Solid state relays provide a more reliable and faster means to switch loads on and off in a secondary region. When compared to mechanical relays, solid state relays have a much longer cycle life and can turn loads on and off much faster. One of the challenges with solid state relays is that they require a constant charge on the control gate. As such, this constraint requires the control circuit to be constantly operating, which can reduce the battery life when the control circuit is a portable device, as is often the case when a separate power source is not provided for the control circuit.
The prior art solid state relay 100 shown in FIG. 1 uses a capacitor 102 to isolate the solid state switch SW1 and SW2 from the primary side to the secondary side. In 24 VAC systems, the ground line is not available, and only the VAC line (common) and the load lines are available. Because there is no ground line, there is no robust supply path on the secondary side. Therefore, the power to charge the gates of SW1 and SW2 is provided by continuously clocking the isolating capacitor 102 that is tied to solid-state relay 100. This continued clocking consumes continuous power from the primary side. In many cases, the primary side is battery powered, and therefore, the battery power is consumed.